Equalis Data Acquisition and Control Systems in action

The Equalis Data Acquisition and Control Systems (DACS) module [1] allows a user to define a mathematical model of a typical control system in the form of a block diagram. From this model you can view critical charts and important characteristics of that system such as step response, Bode, Nyquist Nichols, Pole-Zero, and Singular values plots.

In this example we use our Control and Power Systems module from DACS to analyze a linear model of a permanent magnet DC motor. This motor can be modeled as shown below.

Assuming a constant load, we can consider a DC motor as a SISO sysem, where the applied voltage Va is the input and the motor speed is the output. Using standard mathematical operations (such as summation, gain, integration), let us create a diagram of this SISO system.

The resulting diagram is shown below:

The input Va can be connected to a constant block (this means a constant voltage).

The output w is the speed in rad/s.

Let us use Simulation>Set context to set the following values of constants which appear in the diagram:

J=3.2284E-6; b=3.5077E-6; K=0.0274; R=4; L=2.75E-6;

Now let us analyze the obtained SISO system using the Control and Power Systems module.

For example, let us build a Bode plot. To do this, we open the Linear Analysis palette and place two Operating_Point blocks and one Bode block.

The Operating_Point blocks indicate inputs and outputs of a linear system or subsystem in a diagram.

The only parameter an Operating_Point block is its name (the names of different blocks should be unique).

Let us set the names of two Operating_Point blocks as "begin" and "end" and connect them as displayed follows:

The role of Bode block is to build a bode plot of a SISO system located between two operating points ("begin" and "end").

Let us set its parameters as follows:

When at least one Bode block is present in the diagram and the user clicks Simulation->Start, the system displays a Bode plot. To run a transient simulation the user can (temporally) remove or disable the Bode block.

Now let us start simulation. We will see Bode plot of the transfer function of our system.